Helical Sense-Responsive and Substituent-Sensitive Features in Vibrational and Electronic Circular Dichroism, in Circularly Polarized Luminescence, and in Raman Spectra of Some Simple Optically Active Hexahelicenes
Helical Sense-Responsive and Substituent-Sensitive Features in Vibrational and Electronic Circular Dichroism, in Circularly Polarized Luminescence, and in Raman Spectra of Some Simple Optically Active Hexahelicenes
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DOI：
10.1021/jp4105695
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发表时间：
2014-01-23
影响因子：
3.7
通讯作者：
Lightner, David A.
中科院分区：
文献类型：
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作者：
Abbate, Sergio;Longhi, Giovanna;Lightner, David A.
制备了4种不同的六螺旋烯，5-偶氮六螺旋烯(1)、六螺旋烯(2)、2-甲基六螺旋烯(3)和2-溴六螺旋烯(4)，并分离了它们在室温下稳定的对映体。测定了化合物1的振动圆二色性（VCD）光谱；记录了所有化合物的电子圆二色性（ECD）和圆偏振发光（CPL）光谱。通过密度泛函理论（DFT）确定每种类型的实验谱与相应的理论谱进行比较。根据Nakai等人最近发表的论文，这种比较可以识别出与螺旋度相关的一些特征，以及螺旋骨架上取代基的一些典型特征。从这个角度考察了化合物1的拉曼光谱。
Four different hexahelicenes, 5-aza-hexahelicene (1), hexahelicene (2), 2-methyl-hexahelicene (3), and 2-bromo-hexahelicene (4), were prepared and their enantiomers, which are stable at r.t., were separated. Vibrational circular dichroism (VCD) spectra were measured for compound 1; for all the compounds, electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) spectra were recorded. Each type of experimental spectrum was compared with the corresponding theoretical spectrum, determined via Density Functional Theory (DFT). Following the recent papers by Nakai et al., this comparison allowed to identify some features related to the helicity and some other features typical of the substituent groups on the helical backbone. The Raman spectrum of compound 1 is also examined from this point of view.